KR20160122193A - Submersible power plant - Google Patents

Abstract

The present invention relates to an underwater power plant (1). The power plant 1 includes a structure 2 and a vehicle 3. The vehicle (3) is arranged to be fixed to the structure (2) by at least one tether (4). The vehicle 3 is arranged to move into a predetermined orbit by the fluid stream passing through the vehicle 3. [ The vehicle 3 comprises a first wing 5 and a second wing 6 with the first wing 5 being arranged at a first distance D1 from the second wing 6 in the longitudinal direction, The first wing 5 is disposed at a second distance D2 from the second wing 6 in the transverse direction.

Description

[0001] SUBMERSIBLE POWER PLANT [0002]

The present invention relates to a submersible power plant. The power plant includes a structure and a vehicle. The vehicle is arranged to be secured to the structure by at least one tether. The vehicle is positioned to move into a predetermined trajectory by the fluid stream passing through the wing.

Underwater power plants are known in the art from EP 1816345. In EP 1816345 the plant includes a single wing with a nacelle containing a turbine and a generator attached to the wing. The generator is arranged to move into a predetermined orbit by the fluid stream passing through the wing.

A body with a wing moving through the fluid experiences an induced drag. This induction drag reduces the efficiency of the wing and reduces the lift force. At the end of the wing, fluid creates a wing tip vortice and flows from the underside of the wing to the top of the wing, reducing the effective angle of attack above. Thus, the induced drag of the wing due to the fluid flowing over the wing leads to the wing having a large area to produce the desired lift, i.e., the induced drag reduces the overall efficiency of the wing. The vehicle at the plant in EP 1816345 operates on algae, which can vary greatly in speed. For the fluid stream to propel the vehicle in the low velocity stream, the wings of the vehicle in the plant above EP 1816345 require a large plan area to produce the lift required to achieve the desired vehicle velocity. This leads to the fact that the power plant can be both difficult to manufacture and handle.

EP 1816345 discusses the possibility of having a vehicle that is disposed on a plane portion of each other and has two or more wings separated by spacing elements. Having two wings on each other's flat surface does not address all of the problems mentioned above, since such a solution leads to a large pressure gradient across the wings and reduces the efficiency of the wings. Therefore, improved underwater power plants are needed.

It is an object of the present invention to provide an inventive underwater power plant in which the aforementioned problems are at least partially avoided. This object is achieved by the features of the feature of claim 1.

The present invention relates to an underwater power plant. Power plants include structures and vehicles. The vehicle is arranged to be secured to the structure by at least one tether. The vehicle is positioned to move into a predetermined trajectory by the fluid stream passing through the vehicle. The vehicle includes a first wing and a second wing, wherein the first wing is disposed at a first distance from the second wing in a longitudinal direction and the first wing is disposed at a second distance from the second wing in a lateral direction.

By using two wings and separating the wings in the longitudinal and transverse directions, the area of each of the wings can be reduced while still maintaining the same efficiency. Alternatively, the two wings having the same total area as the wing of the prior art vehicle have increased lift over drag ratio and thereby increased efficiency.

Placing the two wings directly on one another's planes leads to the interaction of the pressure fields created around each wing by amplifying the low and high pressure zone around the wing. The resulting large pressure gradient leads to the problem of swirl generation and flow separation. The present invention instead positions the wings laterally apart, which leads to the interaction of the different pressure bands by weakening the pressure gradient.

One alternative solution may be to have two longitudinally arranged wings with one wing behind the other in essentially the same longitudinal plane. In this case, the wing tip vortex generated by the first wing occurs simultaneously with the wing tip vortex generated by the second wing hand. This will amplify the wing tip vortices so that the overall induced drag is essentially the same as if the vehicle contained only one wing. This configuration thus leads to a less effective wing configuration.

By separating the wings not only in the longitudinal direction but also in the transverse direction, the vortices generated by the first wing and the second wing, respectively, are separated. This is accomplished by placing the two wings directly as described above on the plane of each other or by placing two wings in a longitudinal direction with one wing behind the other in essentially the same longitudinal plane Leading to a significant reduction in effects. The first wing is preferably located in the transverse direction, on the second wing, and in the longitudinal direction, the front of the second wing. This arrangement results in a higher degree of swirl separation than the opposite.

The induced drag can be described mathematically as an equation

(1)

(One)

(2)

(2)

Here, C_ Di is a minimum coefficient of the lifting element in the flow direction, C_L is the lift coefficient, α_i is derived for each, A is the aspect ratio of the wing, D_i is the induced drag, W is the weight of the wing and also the lift L Where q is the dynamic pressure and b is the span of the wing. A more detailed description is given in Fluid-Dynamic Drag, Practical Information on Aerodynamic Drag and Hydrodynamic resistance, Sighard F. Hoerner (1965, 1992); Hoerner Fluid Dynamics, Bakersfield, USA; LCCN 64-019666.

Reducing the lift to half results in a reduction of the induced drag by a factor of four. A vehicle having two wings with lifting forces corresponding to lift of one wing, i.e., each wing having half the lifting force of the original wing, is compared to the vehicle in EP 1816345, for example, You will have an induced drag of half the induced drag of the vehicle with the wing.

The first right end of the first wing and the second right end of the second wing are connected by a first hydrodynamic element and the first left end of the first wing and the second left end of the second wing are connected by a second hydrodynamic element Whereby the first and second wings form a closed wing. The closed wing does not have a wing tip to create a wing tip vortex. This configuration results in reduced overall drag, thereby resulting in increased efficiency. Due to the closed wing configuration, the area of the wings can be made smaller by reducing the wing length. This leads to the vehicle becoming more compact and thereby easier to handle during installation and maintenance. The fact that the wings can be made smaller while maintaining the area efficiency creates the opportunity for a variety of vehicle designs for improved power plants. A closed wing with the same overall plan as a vehicle with only one wing will experience reduced induced drag, leading to a more efficient vehicle, a vehicle of greater lift that produces greater force and speed. A flooded wing that produces the same overall lift as a vehicle with only one wing can have a smaller plan form due to the reduced induced drag, leading to lower friction or viscous drag.

The shorter wing length further enables the vehicle to rotate more sharply without increasing the risk of stalling of the inner wing tip. The smaller turning radius leads to the fact that the plant can be installed in a location with a depth less than previously possible, since the distance from the surface and the bottom to the deepest and shallower point of the orbit can be reduced.

The hydrodynamic elements forming the closed wing can be fluid dynamically shaped. The transversely extending hydrodynamic elements can be used as transverse wings if they are shaped hydraulically. This enables easier rotation of the vehicle. Due to the fact that the vehicle of the power plant is attached by a tether, the vehicle does not bank like an airplane but instead yaws when changing direction along a predetermined trajectory.

For example, as in the case of transverse wings, transversely extending hydrodynamic elements provide a vehicle with transverse steering surfaces that produce the lift required by the yaw to rotate the vehicle.

Furthermore, by having a closed wing with hydrodynamic shaped hydrodynamic elements, no wing tip vortices are generated from the vertical plane, where horizontal wings and effects can be achieved, i.e. if there are winglets that are not closed wings, .

The vehicle may include a nacelle having a generator, wherein the generator is attached to the turbine, and the nacelle is positioned between the first wing and the second wing. By installing a vehicle with a nacelle that includes a generator attached to the turbine, the vehicle can produce power by turning the turbine when the vehicle runs through the fluid, thereby rotating the generator. By having the vehicle with the wing structure according to the present invention, the efficiency of power production can be increased by allowing the vehicle to be made smaller while maintaining efficiency or by maintaining the size of the vehicle. It is also possible to draw power from other components of the power plant, for example by attaching a linear generator or winch to the tether. The power is then produced from the distance between the vehicle and the foundation in the orbit. As most or all rudders are located between the wings, the vehicle according to the present invention further enables more protection against rudder.

The first wing and the second wing may have the same shape or may have different shapes. If the first wing and the second wing have the same wing shape, this leads to an easier and less expensive manufacturing process since there is no customization for any wing. It is also less expensive to have replacement wings when a single type of wing can replace both the first wing and the second wing. If the first wing and the second wing have different wing shapes, it is possible to tailor the hydrodynamic properties of the vehicle to specific positional conditions, thereby further increasing the efficiency of the vehicle. It is also possible to match the vehicle so that the power plant can be located at a location with a shallower depth than prior art power plants as the turning radius is reduced. In addition to having the same or different shapes, the first wing and the second wing may have the same or different plan area and further increase the likelihood of matching.

The pitch angles of the first wing and the second wing can be adjusted relative to each other. This makes it possible to steer in the pitch direction of the vehicle. In addition to enabling the vehicle's increased steering capability, the wings can also be pivoted to an emergency brake position where the vehicle is not propelled by the fluid stream. In the emergency braking position, the pitch angle of the wings is adjusted to a position where forces acting on each wing by the incoming fluid stream are closed to balance or balance, and the vehicle is essentially free of movement in the water Lt; / RTI > Emergency braking may be used if the vehicle fails and needs to be repaired, or if the speed of the vehicle exceeds the designed speed, resulting in structural damage to the vehicle or other parts of the power plant.

The tether may be attached to the vehicle by struts. The front struts are attached to the first wing and the back strut is attached to the second wing. By dividing the wings in the longitudinal direction, it is possible to attach struts to both wings to attach the tether to the vehicle. Dispersing the wing region in the longitudinal direction leads to an increase in pitch inertia, where pitch is the rotation about an axis parallel to the wing length. The increase in pitch inertia is caused by two phenomena. Since the mass is transferred from the center of gravity, an increase in inertia is caused. This can result from rigid body dynamics. An additional increase in inertia results from an increase in the surface moving through the water. Accelerating the body in a fluid adds inertia because more fluid needs to be displaced; This is known as added mass. Separating the first wing and the second wing in the longitudinal direction causes a substantial increase in added mass when pitching the vehicle. One advantage of this configuration is that the need to stabilize the torque from the tether is reduced. This allows the use of shorter struts to reduce drag from the struts. By attaching the front struts to the first wing and the back strut to the second wing, the vehicle will experience further increased pitch stability due to the increased distance between the front and back struts. Increasing the distance between the attachment points to the front and back struts increases the moment of inertia around the point where the struts are attached to the tether. Further, this allows the use of shorter struts to be used in this configuration. The shorter struts simplify the installation and maintenance of the vehicle. The reduction of the drag is caused by the reduced area of the shorter struts.

For example, the wings may be made of metal, various laminates, or combinations thereof. Carbon fiber laminates and glass fiber laminates are two possible laminate options. Other materials may also be considered. By shortening the wing length, it becomes possible to use a laminate and a lighter weight material. For example, the smaller wings also lead to a lower material cost of the vehicle, since thinner walls or beams can be made of less expensive materials such as glass fiber laminates. The use of glass fiber laminates can further reduce the risk and design cost associated with bimetallic / galvanic corrosion of the attached / installed metal parts in prior art vehicles.

The vehicle is equipped with steering means and the control unit is arranged to provide a control signal to the steering means to steer the vehicle in a predetermined orbit. The steering means may comprise one or more control surfaces located on either or both of the first and second wings.

The vehicle of the power plant according to the present invention may take an emergency position. In the emergency position, the pitch angles of the first wing and the second wing are adjusted relative to each other such that the net lift produced by the fluid stream passing through the wings of the vehicle is zero or close to zero . This means that the vehicle is not propelled by the fluid flow and the vehicle will not continue along its predetermined trajectory.

1 schematically shows a power plant according to the present invention.
2 is a side view schematically showing a vehicle of a power plant according to the present invention.
3 is a front view schematically showing a vehicle of a power plant according to the present invention.

Fig. 1 schematically shows a power plant 1 according to the present invention. The power plant 1 includes a structure 2 and a vehicle 3. The vehicle (3) is arranged to be fixed to the structure (2) by at least one tether (4). The vehicle 3 includes a first wing 5 and a second wing 6. The vehicle 3 is arranged to move into a predetermined trajectory by the fluid stream passing through the wings of the vehicle 3. [ The vehicle 3 further comprises a nacelle 7 having a generator. The nacelle (7) is attached to the turbine (8). The nacelle 7 is positioned between the first wing 5 and the second wing 6. In Figure 1, the vehicle 3 includes a closed wing. Closed wing is explained in more detail below. It is also possible for the vehicle 3 to have two separate wings with one or both wings with winglets, without winglets or two separate wings. In Fig. 1, the structure 2 is seen to be placed under the vehicle 3, which may be, for example, the marine or ocean floor. It is also possible that the structure 2 is located above the vehicle 3. In this case, the structure 2 may be a boat, a bridge, a quay or a similar structure.

2 is a side view schematically showing the vehicle 3 of the power plant 1 according to the present invention. The vehicle 3 is located in a reference frame and has a transverse extension along the y-axis of the reference frame and a longitudinal extension along the x-axis of the reference frame. The x-axis extends in the direction from the back surface of the vehicle 3 toward the front surface of the vehicle 3. [ The y-axis extends in a direction perpendicular to the x-axis from the bottom of the vehicle to the plane of the vehicle. As can be seen from Figure 2, the first wing 5 is located in the second wing 6 in the longitudinal direction, measured from the front edge 5a of the first wing 6 to the front edge 6a of the second wing 6, 6 at a first distance D1. The first wing 5 also has a second distance in a lateral direction from the second wing 6, measured from the lower surface 5b of the first wing 6 to the lower surface 6b of the second wing 6, D2. The first and second distances D1 and D2 are between 0-b, specifically between c-b / 2, where b is the span width and c is the chord length of the wings.

The first distance and the second distance D1 and D2 can of course be measured from different points on the first wing and the second wing 5,6. .

The hydrodynamic elements 14, 17 may take any suitable form of the plan to obtain the desired properties.

The front strut 9 is attached to the first wing 5 and the back strut 10 is attached to the second wing 6. The front strut 9 and the back strut 10 are attached to the tether 4 with a tether coupling 11.

3 is a schematic front view of a vehicle 3 of a power plant according to the present invention. Figure 3 shows that the first right end 12 of the first wing 5 and the second right end 13 of the second wing 6 are connected by a first hydrodynamic element 14, The first left end 15 of the first wing 5 and the second left end 16 of the second wing 6 are connected by a second hydrodynamic element 17, Indicating that the wing 6 forms a closed wing. The nacelle 7 further includes a rudder 18 located at the back end of the nacelle. As shown in FIG. 3, the rudder 18 is partially shielded by the closed wing. This increases the protection of the rudder from debris. The hydrodynamic elements 14, 17 may take the form of an airfoil to obtain the desired properties. 3, the closed wing has a square connection between the wings 5, 6 and the hydrodynamic elements 14, 17. The connection between the wings 5, 6 and the hydrodynamic elements 14, 17 may also be rounded so as to obtain a more annular shape. Proper connection between the different types of wings 5, 6 and the hydrodynamic elements 14, 17 can also be considered.

Reference signs in the claims should not be construed as limiting the extent of what is protected by the claims, and their unique function is to make the claims more readily understandable.

As will be realized, the invention is capable of modifications in various obvious respects, all without departing from the scope of the appended claims. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

Claims (10)

An underwater power plant, wherein the underwater power plant (1) comprises a structure (2) and a vehicle (3), the vehicle (3) being secured to the structure by at least one tether ; The vehicle 3 is arranged to move into a predetermined trajectory by a fluid stream passing through the vehicle 3,
The vehicle (3) comprises a first wing (5) and a second wing (6), the first wing (5) being arranged at a first distance in the longitudinal direction of the second wing (6) Wherein the first wing (5) is disposed at a second distance of the second wing (6) in the transverse direction. The method according to claim 1,
The first right end 12 of the first wing 5 and the second right end 13 of the second wing 6 are connected by a first hydrodynamic element 14 and the first wing 5 The first left end 15 of the first wing 6 and the second left end 16 of the second wing 6 are connected by second hydrodynamic elements so that the first wing 5 and the second wing 6, 6) forming a closed wing. 3. The method of claim 2,
Wherein the hydrodynamic elements (14, 17) are fluidically shaped. 4. The method according to any one of claims 1 to 3,
The vehicle 3 comprises a nacelle 7 with a generator and the nacelle 7 is attached to a turbine 8 and the nacelle 7 is connected to the first wing 5 and the nacelle 7, And the second wing (6). 5. The method according to any one of claims 1 to 4,
Wherein the first wing (5) and the second wing (6) have the same shape. 5. The method according to any one of claims 1 to 4,
Wherein the first wing (5) and the second wing (6) have different shapes. 7. The method according to any one of claims 1 to 6,
Wherein the first wing (5) and the second wing (6) have the same planform area. 7. The method according to any one of claims 1 to 6,
Wherein the first wing (5) and the second wing (6) have different plan foam areas. 9. The method according to any one of claims 1 to 8,
Wherein the pitch angles of the first wing (5) and the second wing (6) can be adjusted relative to each other. 10. The method according to any one of claims 1 to 9,
The tether 4 is attached to the vehicle 3 by struts 9 and 10 and the front struts 9 are attached to the first wing 5 and the rear strut 10 is attached to the second wing 6 (1). ≪ / RTI >

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